
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>

    <div id='div'>hello word</div>
    <button id='btn1' onclick='changeColor()'>变为红色</button>
    <button id='btn2' onclick='recover()'>恢复</button>
    <script>
        
        const div1 = document.getElementById('div')

        function changeColor(){
            div1.style.color = 'red'
        }
        function recover(){
            div1.style.color ='black'
        }



    </script>
</body>
</html>